Estimation of Coal Quality Using Indicator Kriging Applied to Data Obtained By Borehole Geophysical Logging

APCOM 2009
João Felipe Coimbra Leite Costa, Jair Carlos Koppe, Paulo Salvadoretti,
Abstract Mineral resources estimation comprises basically two stages: (i) data collection, analysis and validation, and (ii) the estimate of the grades and tonnes of the deposit. The most often applied method for sampling survey in mineral exploration is rotary drilling with total core recovery. High drilling costs make borehole geophysical logging attractive to obtain the maximum possible information from each borehole helping to understand ore intersections, grades variability, limits of the deposits and continuity of the mineralization. In this paper, borehole geophysical logging was used to enhance the sampling survey and to derive grades indirectly (without lab analysis) with a certain amount of uncertainty. Indicator kriging (IK) was the estimation method used, as it is adequate to incorporate the uncertainty associated with the geophysical derived grade values. The results were compared to the conventional procedures using grades determined via core analysis and ordinary kriging. Borehole geophysical logging proved to be essential to define the features of ore deposit and IK provided results with acceptable precision and accuracy if compared to the model provided by ordinary kriging.
Keywords: Borehole logging, Gama-gama, Ash, Geophysics, Indicator, Kriging, Coal, Quality, Estimation, Density
Full Access to Technical Paper
PDF version for $20.00
Other papers from APCOM 2009